BirdAnalyst
Species · Florida · BBS 2025 Release · 1966–2024

Least Tern Population Trend in Florida

All statesWetland birds

Least Tern in Florida has collapsed: down 98% on the route-weighted index since 1968.

-98%Since 1968TrendPercent change in the route-weighted abundance index between a smoothed baseline window and the most recent one. It tracks direction, not absolute population.Full methodology →
50Routes In StateSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
58YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Least Tern Trends in FloridaNotable signalsLong-arc shifts the engine flags automatically — sustained declines or increases large enough to stand out from year-to-year noise.Full methodology →

long arc declinecomputed indexTrend sourceWhether the figure is our own computed route-weighted index or an official USGS modeled estimate. The current build labels every trend as computed.Full methodology →

Least Tern has collapsed in Florida: down 98% on the route-weighted index since 1968.

Least Tern Population Forecast in Florida

If the recent trend holds, Least Tern in Florida is projected to fall about 100% by 2029 — from 0.10 in 2024 to a central estimate of 0.00 (95% range 0.00–3.4). A 5-year backtest shows a typical error of ±498.3%, with 100% of held-out values landing inside the 95% band.

-100%Change by 2029TrendPercent change in the route-weighted abundance index between a smoothed baseline window and the most recent one. It tracks direction, not absolute population.Full methodology →
0.00Projected 2029 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–3.495% range95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →
±498.3%Backtest errorBacktest errorTypical error when we hold out the most recent years, forecast them, and compare to what actually happened. Lower means a more trustworthy projection.Full methodology →
If the recent trend holds, Least Tern in Florida is projected to fall about 100% by 2029 — from 0.10 in 2024 to a central estimate of 0.00 (95% range 0.00–3.4). A 5-year backtest shows a typical error of ±498.3%, with 100% of held-out values landing inside the 95% band.19662029
Projection of the recent trend (dashed) with 80/95% bands — a projection, not a prediction. Habitat, climate, and land use are not modeled.
YearProjected indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →95% low95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →95% high95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →
20250.000.003.4
20260.000.003.4
20270.000.003.4
20280.000.003.4
20290.000.003.4

Least Tern Survey Routes in Florida

Routes recording Least Tern in Florida.
Recent countThe raw number of individuals recorded on this route in its most recent survey year. A single-route tally, not a trend.Full methodology →
Santa Rosa9720031987
Ft Waltn Bch2620111966
St Lucie1720021995
Key Largo1619911987
Merritt Isl1520081991
Key West819871987
Citrus Park820091990
Boca Raton619941968
Scottsmoor520241968
Plantation K520041966
Indiantown420171969
Sandy420072002
Indiantown 2320222019
Sugarloaf Key 2320182005
Alligator Pt319881988
Homestead320072007
Punta Gorda220141980
Ft Gadsden220141969
Dale Mabry219881973
Belmore219721972
Mabel219681968
Childs219771977
Salvista219781969
Broward219731968
Doctor Inlet220001998

Least Tern Population Trend in Other States

alabamaarkansascaliforniacoloradodelawaregeorgiaillinoiskansaskentuckylouisianamainemarylandmassachusettsmississippimissourinebraskanew-jerseynew-yorknorth-carolinaoklahomasouth-carolinatennesseetexasvirginia

Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22.